1. Field of the Invention
The present invention concerns a stabilized aqueous isothiazolone formulation. More in particular, it relates to an aqueous formulation containing an isothiazolin-3-one compound which is useful as non-medicinal biocide and, in particular, useful for antiseptic or antifungal treatment of various emulsions of synthetic polymer.
2. Description of the Prior Art
Isothiazolone compounds such as 5-chloro-2-methyl-isothiazolin-3-one and 2-methyl-isothiazolin-3-one have been known so far as non-medicinal biocide, antiseptic or antifungal agent which are useful, in particular, as antiseptic or antifungal agent for emulsions of synthetic polymer such as NBR latex, SBR latex or acrylic resin emulsion.
Since the isothiazolone compounds are easily water soluble, it is desirable to use them in the form of an aqueous solution in view of dispersion into systems to be treated, flammability of products and also from an economical point of view. Referring to the flammability, those products formulated only with a glycol solvent exhibit a flammability.
Sufficient care has to be taken for flammable products so as to prevent the occurrence of fire accident or spread thereof. Therefore, flammable products are hard to be dealt with, especially in storage or transportation.
Accordingly, flashing products are difficult to handle and non-flammable products are desired also for biocides. However, since isothiazolone compounds are hydrolyzed in water in a short period of time, a mere aqueous solution thereof is extremely instable as formulations and can not be put to practical use at all.
In view of the above, an aqueous formulation has been prepared by forming an isothiazolone compound as a complex with a metal salt such as calcium salt or magnesium salt and then dissolving the complex in water or an aqueous solvent for providing stability or an organic solvent formulation has been prepared by dissolving an isothiazolone compound in a great amount of organic solvent with a small amount of water thereby remarkably reducing the water content (Japanese Patent Laid-Open Sho 61-56174 and 61-212576).
However, if the conventional aqueous formulation as described above is added as it is by an effective amount as an antiseptic or antifungal agent to emulsions of synthetic polymer, there is a problem that the emulsion phase is broken to cause phase separation or coagulation (so-called emulsion shock) due to the effect of polyvalent metal ions such as of calcium or magnesium contained in the formulation.
Accordingly, it is necessary upon using such an aqueous solution to sufficiently dilute the same, but this may cause a disadvantage of lowering the quality such as variation off the latex concentration in the emulsions of synthetic polymer as an object for the treatment. Further, coagulation may some time occur even if the additive is used after dilution. In addition, there has been also proposed a use off such an aqueous formulation with no dilution with emulsions of synthetic polymer, but it is necessary to use a special anionic surface active agent in combination (Japanese Patent Laid-Open Sho 60-650421 and Sho 60-96652).
Further, if the organic solvent Formulation as described above is added to emulsions of synthetic polymer, the organic solvent introduced locally at a high concentration in the system tends to cause a shock depending on the case.
The present invention has been made in view of the foregoing situations and it is an object thereof to provide an isothiazolone compound formulation which is excellent in the stability of the formulation, free from the problem of flammability and inexpensive from an economical point of view, as well as causes no shock when added directly to emulsions of synthetic polymer.
Although there has been a suggestion of combining a compound of the ingredient (a) and a compound of a ingredient (c) used in the present invention in a non-aqueous formulation (Japanese Patent Publication Sho 60-54281 and Japanese Patent Laid-Open Sho 63-316702), combination of them in an aqueous formulation and the effect obtained therefrom have not yet been known at all.